Optimization of high temperature energy storage properties of PEI‐based composite dielectric based on rapid in‐situ growth of inorganic functional layer

Abstract The serious deterioration of the energy density of polymer energy storage dielectrics in high temperature environment is the main reason to curb the in‐depth application of dielectric film capacitors in the field of modern electrical and electronic engineering. Here, aiming at the problem of low dielectric constant of polymer dielectric, a simple, low‐cost method is proposed to grow inorganic polar functional layer on surface of polymer film in situ, which effectively improves the polarization characteristics of polymer dielectric at high temperature. The in situ growth of Ti(OH) 4 inorganic polar functional layer on surface of polyetherimide (PEI) film noteworthy to improve the energy storage performance of dielectric film. The energy storage density of 4.59 J/cm 2 is obtained at 150°C and 600 MV/m, which is 1.18 times that of PEI film under the same condition. The significant enhancement of high temperature energy storage density can be attributed to introduction of functional layer, which effectively improves the dielectric properties and polarization intensity of dielectric film. Furthermore, the facile preparation method provided in this paper can be applied to various thin films under the premise of controllable cost, which is of great significance to improve the high temperature energy storage characteristics of polymer dielectric.